Method and apparatus for casting an internally flanged tubular member



Nov. 18, 1969 w. c. NOTBOHM 3,478,811

METHOD AND APPARATUS FOR CASTING AN INTERNALLY FLANGED TUBULAR MEMBER 1Filed Aug. 18, 1967 FIG-5 62 INVENTOR WILLARD C. NOTBOHM BY W @flJ M? WV nrromyErs y United States Patent 0 3,478,811 METHOD AND APPARATUS FORCASTING AN INTERNALLY FLANGED TUBULAR MEMBER Willard C. Notbohm,Watertown, N.Y., assignor to The Black Clawson Company, Hamilton, Ohio,a corporation of Ohio Filed Aug. 18, 1967, Ser. No. 661,584 Int. Cl.B22d 13/04, 13/10 US. Cl. 164-94 9 Claims ABSTRACT OF THE DISCLOSUREMethod and apparatus for centrifugally casting a tubular member havinginternal flanges by utilizing a core case having baflles which separatethe interior into central and flange-forming chambers connected by anannular passage at the periphery of the baflle. A first pour of metal ismade into the core case and allowed to solidify at least partially toblock the passages, and then a second pour of the molten metal is madeinto the flange-forming chambers to create integral internal flangeswhen the metal solidifies.

BACKGROUND OF THE INVENTION This invention has special relation to theproduction of large tubular shells for uses such as in dryer drums,suction rolls and other similar tubular members of the type which arewidely employed in the manufacture and/or handling of paper and otherweb materials, and which require the strength characteristics developedby centrifu= gal casting. Shells of this type commonly require theapplication of end heads, particularly in cases such as dryer drums andsuction rolls, which must be secured to the shells in pressre-tightrelation, and a convenient procedure for this purpose is to provideinternal flanges within the shells to which the end heads can be boltedor otherwise secured.

It has been a common practice in producing shells of of the general typeoutlined above to cast the shell centrifugally with essentially thedesired uniform final thickness and then to weld separately fabricatedflanges to the inner surfaces of the shell. This process involvessubstantial added expense both in the welding operation and also in theseparate production of the individual flange members. In addition, somemetals which are commonly used for shells produced by centrifugallycasting cannot be welded successfully, such for example as bronze in thecase of paper machine suction rolls, and it has been a common practiceto cast the shells for such rolls substantially thicker than wouldotherwise be necessary in order to provide adequate wall thickness toreceive the mounting bolts for the associated end heads.

In addition to the present practice as set forth above, pertinentbackground art includes the methods and apparatus disclosed in the US.patents of Rojecki No. 3,263,285, issued Aug. 2, 1966, and Fruitman No.3,293,- 708, issued Dec. 27, 1966, both assigned to the assignee of thisinvention. In Rojecki, a quantity of molten metal is placed into therotating core case having central and flange-forming chambers connectedby annular passages between the baflles and the inner surface of thecore case, and then the central chamber is sealed and pressurized tocause a portion of the molten metal to flow into the flangeformingchamber and create the internal flange when the metal solidifies.

' The Fruitman patent discloses a core case assembly similar toRojeckis, but the molten metal is caused to flow through the annularpassage into the flange-forming chamber by placing a molten materialhaving a specific gravity less than that of the molten metal in thecentral "ice chamber to cause a preset volume of the metal to flow intothe flange forming chamber wherein it solidifies. Then the moltenmaterial is removed, either before or after solidification, to produce atubular casting having one or more internal flanges.

It is also prior art to cast centrifugally an elongated composite tubeby first centrifugally casting an outer metal tube, and aftersolidification thereof has occurred and while the mold is stillrotating, casting a second dissimilar metal into the interior thereof. Acomposite tubular casting results since the second volume of moltenmetal partially melts the first casting and thus fuses the two metalstogether. A diclosure of this process appears in an article entitledComposite Tubing by M. L. Samuels in the June 1962 issue of Materials inDesign Engineering.

SUMMARY OF THE INVENTION A tubular member having at least one internalflange is cast by placing a first preset volume of molten metal into arotating core case having flange-forming and central chambers thereinseparated by a baflie. An annular passage formed between the outerperiphery of the baflle and the inner surface of the core caseinterconnects these chambers and provides for the flow of molten metalbetween the chambers. The volume of molten metal in the first pour is atleast sufficient to fill the entire passage, and after the first pourhas at least partially solidified to block the passage, a second pour ofan additional quantity of molten metal is made into an annular openingto the flange-forming chamber wherein it solidifies and forms asintegral internal flange.

The battle is supported by a baflle assembly which can be removed andpartially reused, and which facilitates pouring of molten metal into theflange-forming chambers. Thus each baflle assembly includes an end damresiliently supported in the core case to support removably a pluralityof radial plugs which in turn support the baflies. These pigs and theend dams define an annular pouring opening to the flange forming chamberwhich allows the second pour of molten metal to be made directly intothe flangeforming chamber. The metal surrounds the plugs, which becomeembedded in the metal when it solidifies and are removed by trimming thefinished casting.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view through thecasting apparatus in accordance with the invention for performing themethod of the invention;

FIG. 2 is a sectional view taken along the line 22 of FIG. 1; and

FIG. 3-5 illustrate schematically the schematically the successive stepsand the method of the invention in conjunction with the apparatus shownin FIG. 1, and with the core case omitted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustratescasting apparatus including a tubular core case 10 supported on androtated by drive rollers 11 which engage drive bands 12 extendingcircumferentially around the outer surface of the case 10. The core case10 is generally tubular in configuration and has a cylindrical innersurface 13 with removable baflie assemblies 14 in each end thereofincluding annular end dams 15 secured in place by the contractioncompensating assemblies 16 which compensate for thermal contractionduring solidification and cooling of the metal. Each of these damsinclude a short tubular portion 18 which engages the inner surface 13 ofthe core case 10, and a radially inwardly extending flange portion 19which tapers toward the center of the core case 10 and partially definesthe annular grooves 20 for receiving molten metal, as will be described.The end dams are constructed of a heat resistant material.

The compensating assemblies 16 are spaced angularly around the core case10 (FIG. 2) and include the inwardly extending brackets 21 which arerigidly secured to the end surfaces 22 of the core case 10 by themounting screws 23. The screws 24 extend through openings 25 in therespective brackets 21 into threaded engagement with the bores 26 in theend dam 15 to permit axial movement of the end dams. The springs 27 areinterposed between the brackets 21 and the heads 28 of the screws 24 andthus urge the end dams toward the brackets 21 and into en gagement withthe adjustable stop screws 29 which are threadedly secured on theinnermost ends 30 of the brackets 21. While the brackets 21 are shown asbeing mounted on the end surface 22, it is within the scope of theinvention to modify these brackets for mounting on the inside surface 13of an elongated core case.

The bafile assemblies 14 also include a plurality of equally spacedplugs 31 having the axially extending arms 32 thereon which support theannular baflle 33 on each of the end dams 14. Specifically, each of thesmall cylindrical plugs 31 is secured in placer on the tubular portion18 of the end dam 15 by a screw 36 which extends centrally through theplug and into an internally threaded bore in the tubular portion 18. Thescrew 36 also secures the axially extending parallel arms 32 in place byclamping one end thereof between the head 38 of the screw and the topsurface of the plug 31 (FIG. 1).

The axially extending arms 32 are disposed parallel to each other andcircumferentially of the core case 10 t define the large openings 46 tothe central chamber 42 The bafiles 33 have inner diameters whichcorrespond to the outer diameter defined by the innermost ends of thearms 32 so that the bafiles 33 can be easily placed on the arms 32 andsecured in place by screws 43 which extend through the ends of the armsand into the bafiles.

Each baffie 33 has an outer diameter which is a predetermined arnountsmaller than the inner diameter of the core case to provide annularpassages 45 of uniform predetermined width between the central chamber42 of the core case 10 and the flange-forming chambers 46 on the othersides of the baffle 33. These bafiles are preferably constructed of aceramic or other material capable of withstanding substantial forces andhigh temperatures without being damaged during the casting operation.They may be constructed in one piece, or they may have several segmentswhich can be assembled and disassembled.

The baffle assemblies 33 are preferably assembled prior to insertion ofthe end dams into the core case 10. Once the bafiles are secured in thecore case, the inner surfaces of the core case and end dams 15 arecovered with a suitable liner 50 of refractory material so that theseparts can Withstand and dissipate the heat from the molten metal whichis to be poured into the core case.

Molten metal is supplied to the core case 10 through pouring basins 52which are movable on the tracks 53 and have elongated discharge spouts54 which can discharge from the metal into the central chamber 42. Inaddition, the annular grooves 20 between the plugs 31 and the inwardlyextending portion 19 of .the end dams 15 permit the metal to be pouredinto the flange-forming chambers 46 without splashing or. damage to thebaflle assemblies 14.

In accordance with the method of the invention, the assembled core case10 is first rotated at a predetermined speed which will cause moltenmetal to assume a uniform thickness on the inside surface of the corecase. The speed is determined in conventional manner depending on themetal being used and the diameter of the core case. The pouring basins52 are then moved'to their advanced position so that the spouts 54project through the openings 40 into the central chamber 42. Apredetermined volume of molten metal is then poured through the basins52 and 4 molten mass60, as shown in FIG. 3, on the inside surface of thecore case 10.

The volume of metal which is poured is suflicient to create a moltenmass having a thickness equal to the width of the annular passages 45.This tubular mass is allowed to solidify at least partially so that thepassages 45 are blocked to further flow of metal therethrough. Anexothermic fluxing metal may be poured into the flange-forming chambers46 through the groove 20 to protect the in side surface of the metal atthe ends of the molten mass against oxidation and scruff accumulation. I

As soon as the metal in the flange-forming chambers 46 has-solidified.sufiicient to block the passages, asecond pourof additional metal ismade into the annular grooves 20 from the pouring basins 52, which havebeen retracted so that the-discharge spouts 54are properly aligned withthe grooves 20. This metal then flows around the plugs 31 and into theflange-forming chambers 46 wherein it builds up to form internal flanges61 on the ends of the tubular mass 60, as shown in FIG. 4. The amount ofmetal which is poured into the flange-forming chambers 46 is dependentupon the desired inner dimension of thefiange 61, which can be variedwithout departing from:the scope of the invention. In some cases itmight be necessary to enlarge the length of the plugs 31 so that thesupport arms 32 are. spaced radially inwardly of, the molten metal whenthe flange-forming metal is filled to the desired level.

The metals utilized in the making of the tubular member can besubstantially any metals capable of being centrifugally cast. Inaddition, the metals utilized to create the internal flanges 61 maydiffer from those utilized tov create thetubular portion 60. Forexample, a metal which becomesvery hard on solidification may be used toform .the tubular section, whereas a softer metalwhich is capable ofbeing welded or heat treated canbe utilized to form the internalflanges.

.0nce the pouring operations are completed, the metal is allowed to cooland solidify. As' the metal solidifies, it contracts in theusualmannerthus applying an axial force which urges the baffles 33 toward eachother. Since the bafile assemblies 14 are held in position by thecompensating assemblies 16, the dams 15 are allowed to slide inwardlyand thus accommodate the thermal contraction without damage to thebaffles 33. Specifically, the forces of contraction cause the baffles 33acting through the arms 32 to slide the dams 15 on the inner surface 13of thecore case. The springs 27 are thus compressed when the screw 24moves relative to the mounting bracket 21. When the solidification iscomplete, the rotation of the core case 10 is terminated and thefinished casting removed therefrom. This is accomplished by unscrewingthe bolts 23 which secure the end dams 15 in place and the bolts 38which securethe arms 32 to-the plugs 31. The end dams 15 are thenwithdrawn from the core case, and usually this requires one or moresharp heavy blows to the dams 15. Once they are removed, the arms 32 canbe disconnected from the baffle 33 by unscrewing the bolts 43. Thebaffles'33 areremoved-by breaking them into sections or by disassemblyin the case of a segmented bafile. This leaves the plugs 31 embeddedinthe axial extension 62 of the metal flange which is cut therefrom, andthusthe plugs 31 are separated from thefinished casting 60 ahaving theinternal into the central chamber 42 wherein it forms a tubular flanges.61a ateeach endthereof,,as seen in FIG. 5.

The invention has thus provided apparatus and, a methodfor forming atubular casting having. integral in ternalflanges by; utilizing .a'rotating core easeahaving the interior divided into central andfiange-formingcham bers separated by abaflie and interconnectedby a.passage betweenthe' periphery of the baffle. -and .the inside surface ofythe core case. A; firstpour is made into the central chamber andallowed to solidify at least partially to block the/passage, andthen asecond pour is made. into. .the flange-forming chamber to formvtheinternal flange. The second pour fuses with the first pour to provide anintegral connection therebetween. The baffle assembly can be assembledprior to insertion into the core case, and it may be easily disassembledfor removal of the finished casting.

While the method herein described, and the form of apparatus forcarrying this method into effect, constitute preferred embodiments ofthe invention, it is to be understood that the invention is not limitedto this precise method and form of apparatus, and that changes may bemade in either without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. A method of casting a tubular member having at least one internalflange, comprising the steps of rotating a tubular mold about its axisat a speed sufficient to cause molten metal to assume a uniformthickness over the inner surface of said mold, said mold having theinterior thereof separated by a baflle into central and flange-formingchambers interconnected by an annular passage of a preset radial widthbetween the outer periphery of the baflle and the inner surface of saidmold, making a first pour of a predetermined quantity of molten metalinto said mold, said predetermined quantity of molten metal beingsufficient to provide a uniform thickness at least equal to said presetwidth, causing said metal to solidify sufficiently to seal said passageand substantially to prevent flow of metal between said flangeformingand main chambers, making a second pour of an additional quantity ofmolten metal into said flangeforming chamber, and maintaining saidrotation until said molten metals have completely solidified to create atubular member having an integral internal flange with a preset innerdiameter less than the inner diameter of the metal in said main chamber.

2. A method of casting a tubular member having an internal flange asclaimed in claim 1, comprising the step of adding an exothermic metalflux to at least said flangeforming chambers after said first pour ofmolten metal into the tubular mold to minimize oxidation and scruffaccumulation therein.

3. A method of casting a tubular member having an internal flange asclaimed in claim 1 wherein said second pour occurs after the metal ofsaid first pour is substantially completely solidified.

4. A method of casting a tubular member having an internal flange asclaimed in claim 1 wherein said first pour is made into said centralchamber and said second pour into said flange-forming chamber.

5. A method of casting a tubular member having an internal flange asclaimed in claim 1 wherein both of said pours are made into saidflange-forming chamber.

6. A method of casting a tubular member having a plurality of internalflanges substatnially as defined in claim 1 wherein said second pour ismade into a plurality of said flange-forming chambers.

7. A method of casting a tubular member having an internal flange asdefined in claim 1, comprising the additional steps of removing thebaflles from said core case and trimming the outer edges of the castingafter said casting has solidified.

8. Apparatus for centrifugally casting a tubular member having aninternal flange therein, comprising a tubular mold mounted for rotationabout the axis thereof, drive means for rotating said mold at a speedcausing molten metal to be distributed evenly over the inner surfacethereof, partition means separating the interior of said mold into amain chamber and a flange-forming chamber, said partition meansincluding an annular end dam proportioned for removably mounting in oneend of said mold and including a tubular portion extending along theadjacent inner surface of said mold, a baffle adapted for mounting onthe inner end of said end dam and having an outer daimeter less than theinner diameter of said mold by a predetermined amount to define withsaid mold an annular passage of predetermined radial widthinterconnecting said chambers, a plurality of plugs releasably securedto said end dam and extending radially inwardly of said tubular portionthereof, an arm secured to the inner end of each said plug and extendingtherefrom axially inwardly of said mold, means releasably securing theaxially inner end of each said arm to each said baflie to support saidbafile in spaced relation with said dam, said plug and said arms beingspaced angularly about the interior of said mold to provide spacestherebetween for admitting a second quantity of molten metal to saidflange-forming chamber after a first pour of molten metal has beensupplied to the interior of said mold in an amount suificient to fillsaid annular passage and has solidified sufiiciently to block saidpassage, and means removably securing said end dam to said mold forremoval after all molten metal in said mold has solidified.

9. Apparatus as defined in claim 1 comprising means resilientlyconnecting said end dams to said mold for effecting compensation forthermal contraction of the metal supplied to said mold.

References Cited UNITED STATES PATENTS 82,466 9/1868 Wilmington 164-913,263,285 8/1966 Rojecki l64-114 3,293,708 12/1966 Fruitman -a 164-1143,430,681 3/1969 Smith et al. 164288 X I. SPENCER OVERHOLSER, PrimaryExaminer ROBERT D. BALDWIN, Assistant Examiner US. Cl. X.R. 164-298, 114

